Manufacturing of Cement Process
The manufacturing of cement was first started in England by a scientist named Joseph Aspadin.
For the first time, the manufacture of cement is named Ordinary Portland Cement (OPC) because when cement comes in contact with water it becomes a hard mass after a certain period and this hard mass is found in the Portland region of England. Looks like stone.
India is the second-largest manufacturing hub after China.
Cement is manufactured by integrating lime components and argillaceous components in a ratio of 3:1.
Lime components can be limestone chalk, seashells, and marl while argillaceous components can be shale clay, blast furnace slag, or slate.
The lime component is used to obtain the component called lime while the argillaceous component is composed of silica, alumina, iron oxide, and other impurities.
Cement can be Manufactured either by Dry process or by Wet process.
Dry Process
Step (i):
The material is collected from the mine to the manufacturing plant with the help of dumpers. The collected material consists of limestone and clay material which are the components of lime and Argillasius components, respectively. The collected material exceeds 80 mm in size.
Step (ii):
The collected material is put into a heavy crusher where the size of the material is reduced to Materials of this size from 80 mm to 60 mm and later are put into a light crusher (tube mill/ball mill). Where the size is reduced to 40-60 mm, it is finally deposited in the tank.
Step (iii):
Now, the grinding material called raw mix is fed into the preheater (heater before rotary kine), and due to this increase in temperature the temperature gradually rises up to 500 °C, and the raw mixture becomes smaller in size nearly (25mm)
Benefits of Preheaters:
(a) It makes the process fast.
(b) Fuel consumption is reduced because the burning time of the Rotary Kiln is get reduced.
Now, this raw mix is fed into a rotary Kiln where the temperature is 800-1000°C, 1000-1200°C, 1200-1500°C.
In three separate zones respectively. The product obtained is of size 8 to 10 mm from rotary Kiln is called clinker.
Rotary Kiln
Dimensions:
Diameter= 3m
Lenth= 100m
Revolution= 3 round in 1 minute
Gradient 1 in 25 to 1 in 30.
Zone-1 (Drying zone):
In this zone, the raw mix is fractioned into a smaller size. In this zone, if there is some water or moisture exists in the raw mix then it is also evaporated.
Zone-2 (Nodule zone):
In this zone, the major breakdown of raw mix occurs. In this zone the calcination of limestone takes place
CaCO3(Limestone) —-> CaO(Lime) + CO2 ↑
Zone-3 (Burning zone):
Now, the raw mix which is also called nodules is sloped down, and the major chemical reaction between ingredients of clinker occurs i.e. lime, silica, alumina, iron oxides.
2CaO + SIO2 –> Ca2SiO4 (C2S)
3CaO + SIO2 –> Ca3SiO5 (C3S)
3CaO + Al2O3 —> Ca3Al2O6 (C3A)
4CaO + Al2O3 —> Fe2O3 (C4AF)
Now, from this rotary Kiln, the product obtained is called clinker which is composed of major and minor compounds.
NOTE:
The obtained clinker has high efficiency of reacting with water and is set immediately (flash set) to prevent this, setting of clinker in the presence of water is done by adding gypsum to a tube mill.
(v) Now, the clinker is cooled to a temperature of 100°C, after colliding it is poured into a tube mill where gypsum is also mixed, and a gray-colored finely ground powder is obtained which is called cement. goes.
(vi) It is packed in 50 kg bags with a 35% volume capacity of 0.035 m3.
(vii) Now after packing it is delivered to the dealers.
Wet Process
In a wet process, the heavier crushed material is made wet in the storage tank before feeding into the tube mill.
In the wet process, the preheater has not used the mix obtained from the tube mill is directly fed into the rotary kiln.
Disadvantages:
- The Process Time Is long
- The Fuel Consumption Is More